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The Wide-Area Decontamination Tool
Citation:
Wegman, K., E. Peraza, E. Detmers, T. Boe, W. Calfee, S. Lee, Joe Wood, P. Lemieux, AND L. Mickelsen. The Wide-Area Decontamination Tool. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-22/049, 2022.
Impact/Purpose:
This report describes the methodology developed for the Wide-Area Decontamination Tool, a tool developed to characterize the cost and time associated with a remediation effort following a biological incident impacting indoor, outdoor, and underground areas. This report details the development of this tool, which began with a detailed review of existing remediation tools, a literature review, and an in-depth statistical analysis of data on different decontamination methods. It also includes detailed calculations which are performed within the tool, as well as a proposed model improvement plan for future work on the tool.
Description:
Large-scale biological incidents at indoor, outdoor, and underground areas have the potential to extensively contaminate these sites, requiring extensive time, money, and resources to successfully decontaminate and allow these areas to be utilized again. Contaminated sites must be sampled to characterize the level of contaminant initially present; waste materials may be removed from the site to reduce the cost associated with decontamination; the site may need to be treated with a decontamination agent; finally, after decontamination, surfaces may need to be sampled again to ensure the level of contaminant has been adequately reduced. The ability to estimate the cost of decontaminating affected areas following such an incident, as well as the time and resources required to do so, is critical to planning and preparedness for a wide-area decontamination effort. This report details the development of a probabilistic model, the Wide-Area Decontamination Tool (WADT), which simulates the overall cost, time, and resource demand associated with the decontamination of a wide-area indoor, outdoor, or underground biological incident. This effort included three elements: 1) a review of existing models to identify important aspects of the decontamination process and calculations that should be considered during the development of the tool, 2) a review of studies on the mock decontamination of indoor and underground transportation sites to determine how similar the three decontamination area types (i.e., indoor, outdoor, and underground) were and to identify relevant data that could be used to facilitate the probabilistic nature of the tool, and 3) an analysis of EPA’s biodecon compendium to develop models for the effectiveness of various decontamination treatment types on various surface materials utilized in the tool. A desktop application was developed to run the probabilistic model estimating cost, time, and resource demands for a wide-area biological incident. Excel workbooks containing the baseline parameters for these models were also developed, allowing users to easily modify any data within the application. A series of equations was defined to characterize each step of the decontamination process, including the sampling of surfaces to define initial contaminant levels, removal of waste from the site area, and the decontamination of surfaces. Driving the decontamination of surfaces is a series of equations and distributions developed to estimate the effectiveness, or efficacy, of a particular decontamination treatment method on a given surface material. This analysis provided a method for estimating efficacy although it should be noted that a more rigorous multivariate analysis may be beneficial to constructing the best possible efficacy model from the available data for future versions of the tool. While the developed application includes most of the desired functionality decided upon at the start of the effort, a model improvement plan was also included to suggest enhancements for future iterations of the tool.